Process of bleaching paper pulp and the like



Patented Apr. 7, 1931 PATENT OFFICE JOHN NEUMANN, OF CHICAGO, ILLINOIS PROCESS OF BLEACHING PAPER PULP AND THE LIKE No Drawing. Application filed March 9, 1925, Serial No. 14,829. Renewed August 6, 1930.

My invention relates to a new and novel process of treating pulp and the like, particularly pulp made from waste materials such as waste paper, aper pulp, Wood pulp, cloth pulp, straw or fi rous pulp, etc., and the like which may be coated, impregnated or wise affected with inks, waxes, paints, tar, greases, dirt and the like, and which pulp or material itself may be of colors other than clear white by removin all of the materials other than the pulp or ody and thoroughly bleaching or cleaning the same so that it is White and satisfactory for use in making up high grade papers and the like, or for other purposes. The invention has among its objects the production of a process which is new, novel, simple, inexpensive, rapid in operation and particularly eflicient and satisfactory for the handling of Waste materials.

Many other objects and advantages of the process and method herein described will be obvious to those skilled in the art from the disclosures herein given.

To this end my invention consists in the novel process herein described, and more particularly pointed out in the claims.

In carrying out the processes herein described, it may be mentioned that any apparatus suitable for the purpose may be employed, although I prefer to use my own type of apparatus set forth in a companion a plication, not necessary to describe in detail erem. The apparatus in itself should provide a container constructed with various conveniences for the handling of the pulp and the baths described andI do not wish to be understood as confining myself to any particular or preferred apparatus.

As to the products to be treated, these may vary, but I shall describe the processes as particularly employed in the treating of waste paper and the like, which aper may be newspaper, catalog paper, oiled: parafined paper and the like, whether the same is printed upon, oiled, or otherwise carries or is impregnated with various products and substances. Various other products such as straw and like materials may be likewise treated.

othertarred or' Before carrying out the processes herein described, this waste product is preferably macerated, shredded or broken up, and may be impregnated With water'or conveyed in a water, mushy condition for convenience in handling. No particular attempt is made in this preliminary part of the process to clean or bleach the pulp, this being more particularly to prepare it for the treatment. This waste matter is then immersed in a bath of the desired temperature, or in a more or less cold bath and the temperature of the bath raised to the desired extent, depending upon the materials to be treated. In most cases, the temperature of the bath is brought to substantially a boiling temperature. The bath itself is really a cleansing one, and is designed to remove ink, waste, tar, dirt and other substances, that is to say, to soften the same and release it from the paper pulp. I prefer to employ a bath of water including what may be termed a de-inking re-agent or solution.

In making up my re-agent for de-inking, I prepare the same substantially of borax, caustic potash, soda ash and soap, and then add this solution to the water, the whole making the bath. I prefer to make up the solution substantially as follows, and in the following proportions of materials: One ounce of borax, one ounce caustic potash, and onehalf pound of soda ash, which are boiled together with water to make substantially three gallons, after whichI add one pound of soap, and prefer a white or potash soap, r this being boiled in with the three gallons referred to. This re-agent or solution is added to the bath water, and while the proportions ma vary, initially I have found as suitable an satisfactory the mixture of ten thousand gallons of water to five hundred ounds of the re-agent. Of course, in some instances the re-agent may be varied for omitting some of the constituents or adding others. I consider that the caustic potash to an extent functions in breaking up and combining the borax and soda ash, while the soap neutralizes and prevents a breaking down of the re-agent.

As mentioned, the bath is of a temperature that may be found satisfactory, preferably 200 F. or thereabouts, there being some cases where a less temperature is satisfactory. By raising the temperature of the bath, there is the natural circulation ofv the bath upwardly'in the tank, and during the process of de-inking or cleaning, the ink, dirt, grease, waste, tar or the like rise to the top where it may be drawn off, skimmed OK or otherwise removed. Additional water may be added from time to time as required.

These products taken off, such as ink, dirt, and other substances, may be thereafter treated in any satisfactory manner to separate them and to recover such parts as may be of value and which may be thereafter used.

a For example, I have found that in treating print paper pulp a great portion of the ink may be recovered and be again converted into a commercial product, as may also the wax, if there is wax present. The particular manner of separating and recovering these waste products need not be described herein as it may be done in an satisfactory manner.

During the period tliat the material is in the bath, I generally prefer to agitate, stir or otherwise keep the bath and contents well mixed up. After the material has been treated a sufiicient time, generally about one-half hour, more or less, and the products referred to have been removed, I then remove the pulp from the bath either by drawing off the bath Water or removing the pulp from the bath.

It is preferred to draw off the bath water as the same receptacle or tank or container may be employed for carrying out the further processes, and this avoids handling the pulp unnecessarily. This water drawn ofi' may be filtered or otherwise cleaned and used over again for other batches of pulp, sufiicient' re-agent being added to maintain the proper strength of the bath.

In the next step, I prefer to subject the pulp to a thorough washing for the desired length of time. Generally about fifteen minutes or so is sufiicient, particularly if the pulp and bath water are stirred or agitated so as to clean thoroughly all particles. This washing water may be then drawn off, or in most cases, it may be utilized as the body or water in the bleachin bath.

For bleaching, I a d a reagent or solution that will have a tendency to whiten the pulp, and I have found satisfactory a bleaching solution of salt and oxalic acid. In

making up this bleaching solution, I have found suitable a solution in substantially the following roportions: One ounce of salt, such as tabl ounces of oxalic acid. These ingredients are each separately dissolved in boiling water and then oured together in water to make substantia say, approximately, a gallon of the so ution. The proportions, etc., WhlOh have herein given are more or less approximate as slight variations are possie salt or the like, and three ble, dependingfupon conditions im ossible to anticipate herein. I consider t at the salt has a function with the oxalic acid, the breaking up the fibers of the 111 is developed 0 or ozone, a liig bleaching agent.

In the bleaching bath, this is made up of approximately ten thousand gallons of water and then about six pounds of the bleaching solution placed in the bath and thoroughly mixed with the water. The bleaching process is continued the desired length of time, and I have found substantially ten minutes or so as sufficient, the temperature being maintained in most cases at a point above 100 F. After'this treatment, the pulp and bath are separated either by removing the pul or more conveniently removing the bat 1 water. The bleaching solution of water and that re-agent I have found may be drawn off, filtered or otherwise cleaned and be used again, there being generally a ly effective suitable addition of fresh re-agent to maintain the strength for future use on a succeeding batch of pulp.

After the bleaching bath has been removed, I then prefer to wash the pulp with fresh water, this being continued to the desired extent, which may, of course, vary in different batches, it bein desired, however,

to wash off or out of t e pulp all of the bleaching bath. The pulp is then ready for such other treatment in the manufacture of paperas may be desired. Generally this last washing water may be used as a means of conveying the pulp to the further treating station.

Succeeding batches of pulp are, of course,

treated in the same manner. There may be slight variations in the treatments with dif and there ferent batches, depending upon the nature a of the waste product which is to be cleaned and prepared, and additional treatments not necessary to describe given if desired.

I have found that cheap waste paper such as print paper employed in newspapers, catalogs and the like, when treated with my processes, produces a very high ade quality of paper pulp of exceptiona whiteness and fineness which may be employed in making u very fine pa ers. As a matter of fact, this same pulp I ave found is satisfactory for making up 8. hi her grade of paper than the waste stock i rom which it was produced. Straw and other fibrous pulp material may be treated in a satisfactory manner.

The process is comparatively sim le is inexpensive, and is highly efiicient. t oes not require expensive and complicated apparatus, and makes possible the utilizing of waste product which may be secured at a very low cost, nettin large returns. It Wlll be noted that not on y is the pulp recovered 'foreign substances or the like,

waxes and the like recovered may be turned into a profit. While I prefer to use my own apparatus for convenience sake and also to more efiiciently carry out the process, it W111 be obvious from the preceding description that special apparatus, while perhaps desirable, is not essential. In the specification and claims where I refer to de-inking, I wish to be understood as including de-inking, de-waxing, or removing grease, dirt and and I also wish to be understood that it is immaterial whether the pulp is left or removed from the bath or the bath drawn off from the container, the results being the same.

Having thus described my invention, it is obvious that various immaterial modifications may be made in the same without departing from the spirit of my invention; hence I do not wish to be understood as limiting myself to the exact process, method and combination of materials herein 'described or uses mentioned,

What I claim as new and desire to secure by Letters Patent is 1. The process of treating paper pulp and the like comprising bleaching the pulp in a bath containing salt and oxalic acid, and then washing the pulp.

2. The process of treating paper pulp and the like comprising bleaching the pulp in a heated water bath containing salt and oxalic acid, and then washing the pulp after the removal of the bath.

3. The process of treating paper pulp and the like comprising bleaching the pulp in a solution of substantially one part of salt to three parts of oxalic acid dissolved in water.

4. The process of bleaching paper pulp onsisting in subjecting the pulp to the action of a bath containing substantially one part of salt to three parts of oxalic acid separately dissolved in boiling water and added to a water bath for such treatment.

In testimony whereof, I have hereunto signed my name.

JOHN NEUMANN. 

